The agency's guidance affects Serevent, Advair, Symbicort and Foradil. Manufacturers will be required to include warnings on their labels.

Reporting from Washington – The Food and Drug Administration on Thursday called for putting new limits on powerful and long-lasting bronchial drugs that millions of Americans use to treat asthma – a move designed to lower the risk of complications leading to hospitalization or even death.

Instead, the FDA said, patients should use products containing only the corticosteroids or other asthma-relieving medication whenever possible.

In addition, patients who cannot control asthma symptoms any other way should use LABAs for the shortest possible time, but the drugs should never be used alone in treating asthma in adults or children, the agency said.

About 95% of LABA users receive the drug through a combination product, according to the agency.

The drugs affected by the FDA action include the LABA-only products Serevent and Foradil, along with Advair and Symbicort, which contain both LABAs and inhaled corticosteroids. All are dispensed in inhalers via prescription.

Manufacturers will be required to include new warnings on the drugs' labels, educate patients and physicians about risks associated with the use of LABAs and study whether using the long-acting compounds in tandem with other drugs makes them safer.

The goal is to manage the risk of LABAs while “keeping them available for patients who really need them,” because alternative options “are not that great,” said Dr. John Jenkins, FDA's director of new drugs and a pulmonologist.

LABAs are also used to treat chronic obstructive pulmonary disease, commonly called COPD, and bronchial spasms associated with vigorous exercise. The FDA's new guidance does not apply to those treatments.

Asthma, a chronic inflammatory lung disease, affects about 23 million Americans, according to the American Lung Association.

The new guidance is based on clinical trial data showing that use of LABAs carries an increased risk of aggravating asthma symptoms leading to hospitalization and, in some cases, death.

LABAs relax muscles in bronchial passages, allowing more air to flow. They provide immediate relief to asthma sufferers but don't address the underlying inflammation, creating the risk of a life-threatening condition.

The FDA action reflects “a conservative approach,” said Dr. Serpil Erzurum, a staff physician at the Cleveland Clinic's Respiratory Institute. “They're saying these drugs are useful and should be kept available.”